The day after four members of the Louisiana National Guard and seven Marines from North Carolina went missing, the base in Hammond was quiet, while residents there anxiously awaited any news.More >>

The day after four members of the Louisiana National Guard and seven Marines from North Carolina went missing, the base in Hammond was quiet. The commanding officer told the media the focus was on the families, while residents in Hammond anxiously awaited any news.More >>

PENSACOLA, FL (WAFB/AP) -

Four soldiers based out of Louisiana and seven Marines based out of North Carolina are missing after an Army helicopter crashed during a night training exercise at Eglin Air Force Base in the Florida Panhandle, according to officials.

Base officials said the soldiers are from a Louisiana National Guard base in Hammond, while the Marines are part of a Camp Lejeune, North Carolina-based special operations group. They added some human remains have washed up on shore. Search and rescue crews remain on scene, but heavy fog is having an impact on their efforts. Officials emphasized it is still considered a search and rescue mission. Multiple agencies are on scene, including the Coast Guard, which have secured waterways.

A Pentagon official said Wednesday morning that the 11 service members are presumed dead. The official spoke to The Associated Press on condition of anonymity because the official wasn't authorized to speak on the record. The UH-60 Black Hawk helicopter went down during a routine training mission on a remote swath of beach between Pensacola and Destin. The beach is owned by the military and is used for test missions.

Officials released more details about the crash in a 2 p.m. news conference that was held at the Louisiana National Guard location in Hammond.

The base in Florida reported two helicopters assigned to the 1-244th Assault Helicopter Battalion in Hammond were participating in a training exercise, when one of them was involved in an accident. It added the helicopter was reported missing around 8:30 p.m. and debris from the helicopter was found around 2 a.m.

Search and rescue efforts continue at the site of the accident. Crews have taken to the air as the fog that had hampered the search begins to lift. A helicopter was flying low over the Santa Rosa Sound on Wednesday afternoon, looking for any sign of the helicopter that crashed or any of the 11 Marines and soldiers that were aboard when it went down. Human remains and small pieces of wreckage from the helicopter have washed ashore.

The search was set continue throughout the night, according to Eglin Air Force Base spokesman Mike Spaits. "There is always room for optimism," he said. "The fog has been hampering our search efforts, and more fog is continuing to roll in."

However, the search was called off Wednesday evening due to poor weather conditions, according to Major Craig Savage with the Air Force. He expects the search to resume at some point Thursday morning.

A military spokesman says the 11 Marines and soldiers involved in a helicopter crash in Florida were using boats and choppers to practice reaching and leaving a target site. Capt. Barry Morris is a spokesman for the Marine Corps Special Operations Command at Camp Lejeune, North Carolina. He says the troops involved with the exercise had been in the Florida Panhandle since Sunday and were scheduled to stay through this Sunday. He says they were doing what the military calls insertion and extraction missions.

Maj. Gen. Glenn Curtis of the Louisiana National Guard said one of the two helicopters on the training mission turned back because of bad weather and the other crashed.

"One of them started to take off and then realized there was a weather condition and turned around and came back," said Maj. Gen. Curtis.

Col. Pete Schneider of the Louisiana Guard said it was unclear exactly when the decision to turn back was made, or whether that was communicated to the crew in the helicopter that crashed. Officials added the pilots in both helicopters were instructor pilots which is the highest level of training and that the rest of the crew had several thousand hours of experience.

Bourland added the Army helicopter took off from a nearby airport in Destin and joined other aircraft in the training exercise. The area where the crash happened Tuesday night was under a fog advisory and the foggy conditions remained Wednesday morning.

Meteorologist Steve Caparotta said it appears as though the visibility at Eglin Air Force Base was fluctuating between one-quarter and three-quarters of a mile due to fog around the time of the crash.

The names of those on board the crashed helicopter have not been released. An investigation is underway into what caused the crash.

President Barack Obama said he's confident there will be a detailed and thorough investigation into the crash. He spoke by phone Wednesday with Maj. Gen. Joseph Osterman, who heads the Marine Corps special forces, and Maj. Gen. Curtis. The White House says Obama expressed his condolences to the families of those killed.

The Coast Guard said the search area is about 50 square miles. Officials reported debris from the crash was first spotted about 1:30 a.m. Wednesday. Search crews on the beach and in the Santa Rosa Sound are still trying to navigate dense fog and light rain.

A woman who lives and works at a campground near where the helicopter crashed said she heard something strange about the time the chopper was reported missing. Kim Urr was sitting outside with a friend around 8:30 p.m. Tuesday at the Navarre Beach campground. Urr said they are used to hearing helicopters and ordnance blasts from the military base nearby, but this sound was different.

"It sounded like something metal either being hit or falling over, that's what it sounded like," she said. "And there were two booms afterward, similar to what you hear with ordnance booms, but more muffled."

She added they knew immediately that something was not right. They listened for sirens, but there were none. On Wednesday morning, they heard lots of sirens.

"It's a tough day when you're responsible. They're under my command so I take very seriously their safety and well-being and that of their families," said Curtis.

Curtis said the crew of a helicopter that crashed off the coast of Florida had a lot of experience, serving in Iraq and helping after Hurricane Katrina and the BP Gulf of Mexico oil spill. He added that they also helped after hurricanes Rita and Isaac.

"Our thoughts and prayers are with the Marines, soldiers and family members of those involved in this mishap. We are working closely with all parties involved to locate our Marines and the Army aircrew as soon as possible," Osterman said in a written release.

Gov. Bobby Jindal also released a statement on the crash.

"This morning, I spoke to the adjutant general of the Louisiana National Guard to offer our prayers and support for the brave service members who are missing from the Blackhawk crash over the panhandle," it read. "Four members of the crew are part of the Louisiana National Guard. Our guardsmen have fought courageously overseas in defense of our nation, and here at home, they have protected what matters most during times of crisis. These soldiers represent the best of Louisiana, and we are praying for them and their families."

The 1-244th Assault Helicopter Battalion received the Founders and Patriots of America's 2012 Outstanding National Guard Unit Award. It is a very active battalion and is known for its rooftop rescues in New Orleans in the aftermath of Hurricane Katrina. A key mission of the 1-244th has been search and rescue operations during hurricanes. Since Katrina, the unit has rescued more than 40,000 Louisiana residents.

Copyright 2015 WAFB. All rights reserved. The Associated Press contributed to this report.